/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */
package org.apache.mina.core.future;

/**
 * An {@link IoFuture} for asynchronous write requests.
 *
 * <h3>Example</h3>
 * <pre>
 * IoSession session = ...;
 * WriteFuture future = session.write(...);
 *
 * // Wait until the message is completely written out to the O/S buffer.
 * future.awaitUninterruptibly();
 *
 * if (future.isWritten()) {
 *     // The message has been written successfully.
 * } else {
 *     // The message couldn't be written out completely for some reason.
 *     // (e.g. Connection is closed)
 * }
 * </pre>
 */
public interface WriteFuture extends IoFuture {
	/**
	 * @return <tt>true</tt> if the write operation is finished successfully.
	 */
	boolean isWritten();

	/**
	 * @return the cause of the write failure if and only if the write
	 * operation has failed due to an {@link Exception}.
	 * Otherwise, <tt>null</tt> is returned.
	 */
	Throwable getException();

	/**
	 * Sets the message is written, and notifies all threads waiting for this future.
	 * This method is invoked by MINA internally. Please do not call this method directly.
	 */
	void setWritten();

	/**
	 * Sets the cause of the write failure, and notifies all threads waiting for this future.
	 * This method is invoked by MINA internally. Please do not call this method directly.
	 *
	 * @param cause The exception to store in the Future instance
	 */
	void setException(Throwable cause);

	/**
	 * Wait for the asynchronous operation to complete.
	 * The attached listeners will be notified when the operation is completed.
	 *
	 * @return the created {@link WriteFuture}
	 * @throws InterruptedException If the wait is interrupted
	 */
	@Override
	WriteFuture await() throws InterruptedException;

	@Override
	WriteFuture awaitUninterruptibly();

	@Override
	WriteFuture addListener(IoFutureListener<?> listener);

	@Override
	WriteFuture removeListener(IoFutureListener<?> listener);
}
